Ecology Gymnosperm Ecology
by
Christopher Earle
  • LAST REVIEWED: 06 June 2017
  • LAST MODIFIED: 30 June 2014
  • DOI: 10.1093/obo/9780199830060-0092

Introduction

The gymnosperms are a group of plants that includes the conifers, cycads, gnetophytes, and ginkgo. The term “gymnosperm” is from the Greek for “naked seed,” meaning that the ovules of these plants are exposed to the air, rather than enclosed within a vegetative structure (the ovary), as are the ovules of angiosperms. There is ongoing debate about whether the gymnosperms are phylogenetically distinct from the angiosperms, but most recent molecular genetic analyses have tended to support that hypothesis. Of the four gymnosperm groups, the conifers are by far the predominant group, dominating forest ecosystems over most of the temperate and boreal zones of the Earth as well as widespread within tropical mountains; accordingly this review focuses on the conifers and discusses the other gymnosperm groups in a concluding section. Of those other groups, the ginkgo includes a single species endemic to a very small area in China. There are two families, ten genera, and about three hundred species of cycads, which are mostly rare endemics in ecosystems dominated by angiosperms. Among the gnetophytes, there are three families, three genera (Gnetum, Ephedra, and Welwitschia), and about one hundred species; Gnetum occurs as a small tree or liana in tropical rainforests, Ephedra mostly occurs as a shrub in semiarid woodlands, and Welwitschia is an utterly unique plant found in the coastal desert of Namibia. Conifers differ from angiosperms in a variety of ways that have implications for their ecological roles; for instance, conifers rely on aromatic hydrocarbons to deter herbivory and disease, are wind pollinated, grow relatively slowly, and live to relatively great ages. Conifer wood is light and easily worked, so humans have exploited the group from the earliest times, and it remains economically important across a spectrum of economic systems and cultures; thus applied conifer ecology is broad field of study. The conifers have low taxonomic diversity (total six families, sixty-seven genera, and about 650 species), and about a third of these species are of conservation concern, in most cases due to human-caused habitat loss, either directly due to changes in land use or indirectly due to climate change or invasive species, especially introduced pests and pathogens. Nonetheless, the conifers are also an emotionally significant group of plants, and people of many cultures seek to protect and restore these plants and their habitats.

General Overviews

The principal overview works for conifer ecology—Bieleski and Wilcox 2009, Burns and Honkala 1990, Debreczy and Rácz 2006, Eckenwalder 2009, and Farjon 2010—are organized taxonomically, reviewing ecological attributes in a systematic context. Several important sources provide partial overviews, organized taxonomically or geographically. Richardson 1998 provides a taxonomic overview for Pinus, and Turner and Cernusak 2011 provides a similar service for the Podocarpaceae. Burns and Honkala 1990 provides a geographic overview for North America, and Enright and Hill 1990 provide the same for the southern hemisphere.

  • Bieleski, R. L., and M. D. Wilcox. 2009. Araucariaceae. Dunedin, New Zealand: International Dendrology Society.

    E-mail Citation »

    The only comprehensive volume addressing this largely tropical family. Many articles address various ecological issues.

  • Burns, R. M., and B. H. Honkala. 1990. Silvics of North America, Vol. 1, Conifers. Forest Service Agriculture Handbook 654. Washington, DC: United States Department of Agriculture.

    E-mail Citation »

    Provides detailed accounts of the ecology and management of sixty-five species of economically important conifers native to North America.

  • Debreczy, Z., and I. Rácz. 2006. Conifers around the world. 2 vols. Budapest: DendroPress.

    E-mail Citation »

    A comprehensive review of conifers native to temperate climates (broadly interpreted, e.g., boreal regions and subtropical Australia). Includes remarks on distribution and ecology. A lengthy introductory section addresses the history of conifer discovery, conservation, systematics, morphology, distribution and climate, and paleontology. A superbly illustrated book with several thousand color photos.

  • Eckenwalder, J. E. 2009. Conifers of the world. Portland, OR: Timber.

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    A comprehensive review of all conifer families, genera, and species that includes some remarks on distribution and ecology of each species. One introductory chapter provides a good overview of conifer ecology.

  • Enright, N. J., and R. S. Hill. 1990. Ecology of the southern conifers. Washington, DC: Smithsonian.

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    Conifers of the southern hemisphere account for nearly half of the diversity of conifer species, but have received little study as compared to species of the northern hemisphere. This volume provides a geographically organized review of ecological studies. See p. 342.

  • Farjon, A. 2010. A handbook of the world’s conifers. 2 vols. Leiden, The Netherlands: Brill Academic.

    DOI: 10.1163/9789047430629E-mail Citation »

    A comprehensive review. For all conifer genera, species, and infraspecific taxa, provides a description and notes on distribution, ecology, conservation status, and human use. Introductory chapters address distribution, ecology, economic importance, and conservation. See p. 1111.

  • Richardson, D. M., ed. 1998. Ecology and biogeography of Pinus. Cambridge, UK: Cambridge Univ. Press.

    E-mail Citation »

    Focused on the pines, which is the largest (about one hundred species) and most economically important genus of conifers. The twenty-two chapters address subjects as diverse as systematics, late Quaternary population dynamics, the role of fire, the evolution of life histories, genetic variation, seed dispersal, ecophysiology, mycorrhiza and soils, diseases and insect interactions, cultivation, and the importance of pines as invasive species.

  • Turner, B. L., and L. A. Cernusak, eds. 2011. Ecology of the Podocarpaceae in tropical forests. Smithsonian Contributions to Botany 95. Washington, DC: Smithsonian Institution Scholarly Press.

    E-mail Citation »

    Podocarps, which represent the third great family of the conifers but have primarily a southern hemisphere distribution, are largely neglected in conifer ecology—seldom studied, but highly distinctive. This work is the first comprehensive study of podocarps in the tropical forest, reviewing their ecophysiology, mycorrhizal symbionts, evolutionary ecology, and other aspects of their surprising coexistence within angiosperm-dominated forests.

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